The goal of this renewal application (2DA07058-17) entitled, "Morphine Actions on the Immune System" is to elucidate the effects of chronic exposure to opioids, such as morphine, on various immune parameters. We propose to examine the interactions between morphine and the bacterial endotoxin, lipopolysaccharide (IPS), during infection with HIV-1, using the HIV transgenic rat (HIV Tg rat) and human cell culture models. The HIV Tg rat carries a gag-pol-deleted HIV-1 genome under the control of the HIV-1 viral promoter, and expresses 7 of the 9 HIV genes. This model shows no viral replication;however, it does develop various manifestations of human HIV infection, indicating that the presence of viral proteins in the host causes HIV progression. The actions of morphine are mediated through the mu opioid receptor (MOR). We found that MOR mRNA in the peritoneal macrophages and brain of the HIV Tg rat was significantly higher than that in control animals, and was further increased following systemic LPS treatment. We also found that in TPA- differentiated HL-60 promyelocytic leukemia cells (TPA-HL-60 cells), treatment with recombinant HIV glycoprotein 120 (gp120) or LPS up-regulated MOR expression, which appeared to be mediated through the actions of the pro-inflammatory cytokine, TNF-a. In addition, inhibition the NFkB1 transcriptional factor decreased the up-regulation of MOR expression by LPS and gp120. We, thus, hypothesize that the MOR signaling pathway serves as a convergence point for the inflammatory response to opioids, bacterial endotoxin, and HIV gp120 viral protein. To test our hypothesis, in Aim 1, we will determine the effects of chronic morphine exposure on LPS-induced leukocyte-endothelial interaction, cytokine production, and intravascular coagulation in HIV Tg rats. In Aim 2, the effects of morphine and LPS, alone and in combination, on MOR expression will be examined in HIV Tg rats. In Aims 3 and 4, the cross-effects of morphine, LPS, and gp120 on MOR expression, cytokine secretion, and the involvement of the NF/fB, AP-1, and STATS transcriptional factors will be examined in TPA-HL-60 cells. Few studies have examined the interactive effects of opioids and bacterial endotoxins in the course of HIV infection using either animal models or human cell cultures. Therefore, the data from the proposed studies can have substantial clinical significance in the understanding and treatment of HIV infection and AIDS.